Allow a callable parameter to decide if require is going to be retrie…

CHANGELOG.md

@@ -5,6 +5,18 @@
 ### Added
 
 - `PluginClientFactory` to create `PluginClient` instances.
+- Added new option 'delay' for `RetryPlugin`.
+- Added new option 'decider' for `RetryPlugin`.
+
+### Changed
+
+- The `RetryPlugin` does now wait between retries. To disable/change this feature you must write something like: 
+
+```php
+$plugin = new RetryPlugin(['delay' => function(RequestInterface $request, Exception $e, $retries) { 
+  return 0; 
+}); 
+```
 
 ### Deprecated
 

spec/Plugin/RetryPluginSpec.php

@@ -101,4 +101,12 @@ function it_does_not_keep_history_of_old_failure(RequestInterface $request, Resp
         $this->handleRequest($request, $next, function () {})->shouldReturnAnInstanceOf('Http\Client\Promise\HttpFulfilledPromise');
         $this->handleRequest($request, $next, function () {})->shouldReturnAnInstanceOf('Http\Client\Promise\HttpFulfilledPromise');
     }
+
+    function it_has_an_exponential_default_delay(RequestInterface $request, Exception\HttpException $exception)
+    {
+        $this->defaultDelay($request, $exception, 0)->shouldBe(1000);
+        $this->defaultDelay($request, $exception, 1)->shouldBe(2000);
+        $this->defaultDelay($request, $exception, 2)->shouldBe(4000);
+        $this->defaultDelay($request, $exception, 3)->shouldBe(8000);
+    }
 }

src/Plugin/RetryPlugin.php

@@ -24,6 +24,16 @@ final class RetryPlugin implements Plugin
      */
     private $retry;
 
+    /**
+     * @var callable
+     */
+    private $delay;
+
+    /**
+     * @var callable
+     */
+    private $decider;
+
     /**
      * Store the retry counter for each request.
      *
@@ -35,18 +45,28 @@ final class RetryPlugin implements Plugin
      * @param array $config {
      *
      *     @var int $retries Number of retries to attempt if an exception occurs before letting the exception bubble up.
+     *     @var callable $decider A callback that gets a request and an exception to decide after a failure whether the request should be retried.
+     *     @var callable $delay A callback that gets a request, an exception and the number of retries and returns how many milliseconds we should wait before trying again.
      * }
      */
     public function __construct(array $config = [])
     {
         $resolver = new OptionsResolver();
         $resolver->setDefaults([
             'retries' => 1,
+            'decider' => function (RequestInterface $request, Exception $e) {
+                return true;
+            },
+            'delay' => __CLASS__.'::defaultDelay',
         ]);
         $resolver->setAllowedTypes('retries', 'int');
+        $resolver->setAllowedTypes('decider', 'callable');
+        $resolver->setAllowedTypes('delay', 'callable');
         $options = $resolver->resolve($config);
 
         $this->retry = $options['retries'];
+        $this->decider = $options['decider'];
+        $this->delay = $options['delay'];
     }
 
     /**
@@ -73,12 +93,30 @@ public function handleRequest(RequestInterface $request, callable $next, callabl
                 throw $exception;
             }
 
-            ++$this->retryStorage[$chainIdentifier];
+            if (!call_user_func($this->decider, $request, $exception)) {
+                throw $exception;
+            }
+
+            $time = call_user_func($this->delay, $request, $exception, $this->retryStorage[$chainIdentifier]);
+            usleep($time);
 
             // Retry in synchrone
+            ++$this->retryStorage[$chainIdentifier];
             $promise = $this->handleRequest($request, $next, $first);
 
             return $promise->wait();
         });
     }
+
+    /**
+     * @param RequestInterface $request
+     * @param Exception        $e
+     * @param int              $retries The number of retries we made before. First time this get called it will be 0.
+     *
+     * @return int
+     */
+    public static function defaultDelay(RequestInterface $request, Exception $e, $retries)
+    {
+        return pow(2, $retries) * 1000;
+    }
 }